How does this work?

[RedWolf]

This isn't exactly a joke - more of a puzzle but it's probably better off here than in Off Topic.


Three guys are in a hotel room and they decide to order a pizza. The total comes to $30 so they split the cost and pay $10 each when the delivery boy arrives (no tip mind you).

The pizza guy gets back to the restaurant and is told "Sorry we made a mistake - the price should have been only $25 - so please take $5 back to the customer"

On the way back the disgruntled pizza boy pockets $2 for himself (after all those cheap guys didn't tip him) and returns $3 to the men who split it evenly.

The question now is "How much did each man pay for the pizza?"

Most people remember that the men each paid $10 originally... AND that by splitting the retruned $3 they should have each gotten $1 back.

$10 - $1 = $9

$9 each is of course the correct answer. Here's the wierd part though that will leave you (and me) scratching your head:


$9 X 3 (men) = $27

$27 + $2 (the money the pizza boy stole) = $29

So where did the other $1 go???


As far as I can tell it just seems to be a quirk in the math system - I've never yet been given a good answer.

I'd love if someone more intelligent than myself in these matters could solve this little puzzle.

 

[Hitro]

You make a simple mistake:

They give $30
The restaurant takes 25$
The delivery boy takes 2$
That is what they pay 25$ + 2$ = 27$; 27 / 3 = 9$ each.

You can't calculate 27$ + the 2$ he stole, these 2$ are already in it because that's among the money they lose. You have to calculate 27$ + the 3$ they get back = 30$.

Was this serious or a joke?

 

[RedWolf]

Originally posted by Hitro
You make a simple mistake:

They give $30
The restaurant takes 25$
The delivery boy takes 2$
That is what they pay 25$ + 2$ = 27$; 27 / 3 = 9$ each.

You can't calculate 27$ + the 2$ he stole, these 2$ are already in it because that's among the money they lose. You have to calculate 27$ + the 3$ they get back = 30$.

Was this serious or a joke?

It was serious. This puzzle stumps EVERYONE usually.

I understand that the issue is in the wording of the puzzle - the problem i think is how the english language translates into math.

It makes sense that you should be able to take the 9 X 3 and add the 2 to get the full price... but it doesn't work...

but it SEEMS like it should... and most people think it should when you tell them the puzzle...

 

[Hitro]

Probably.
It may get confusing if you don't follow it correctly.
The thing is that it doesn't make sense to be able to take 9 x 3 + 2, because the 2 is already included in the 9 x 3. You take the wrong part of the 5 they give back.

 

[RedWolf]

Originally posted by Hitro
Probably.
It may get confusing if you don't follow it correctly.
The thing is that it doesn't make sense to be able to take 9 x 3 + 2, because the 2 is already included in the 9 x 3. You take the wrong part of the 5 they give back.

Ok i see what you mean - and I guess thats the key.

But most people (me included) think at first that you can just add up the the money and get the total. I knew the part about adding the $27 + $3... BUt i thought it should work the other way too.

It may seem realy simple to you - but trust me - this baffles MOST people... I've had brilliant computer programmer friends hear the puzzle and be totally puzzled by it.

I have NEVER until now been given a good explanation. I've even had people say "i think there's a flaw in the way you're thinking about it" but they couldn't pin point the actual problem.

 

[.:KNAS:.]

Oh boy!!! ROFLMAO!!!! this was funny <---- bitter sarcasm....

but nonetheless interesting, but i would have posted it in the OT

edit: but then you ARE a dumb-ass lol j/k

 

[Apollo]

Originally posted by RedWolf
$27 + $2 (the money the pizza boy stole) = $29

This is where you made the mistake. The total cost is the $27, so the $2 tip is in that $27. If you need to do an equation with those two numbers, it should be: $27 - $2 = $25 (the actual cost of the pizza).

 

[Jason Fox]

I think it's one of those things that's easier when you look at it. When I first heard it I kept doing the same thing, adding the $2 to the $27 before I realized that I was thinking about it backwards.